The prior art shows a number of attempts to balance the power introduced between opposed electrodes in a furnace. Many of the prior art attempts used transformers tapped along the length of the secondary with multiple separate taps. These taps provided more or less voltage with respect to each of the other taps.
Some of the prior art examples are shown in U.S. Pat. Nos. 3,852,509, 4,025,713, 3,145,246, 3,147,328 and 2,993,079.
The prior art shows tapped transformers but does not show the use of a transformer secondary providing symmetrical taps and where the voltage magnitude vector corresponds to the distances between the respective electrodes or to the location of the electrodes with respect to the relative distance of the electrodes along the flow channel.